#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i,n) repi(i,0,n)
#define repi(i,a,b) for(int i=(int)a;i<(int)b;++i)
int main(){
    string s;cin>>s;
    rep(i,s.size()){
        if(i%2==0&&!(s[i]>='a'&&s[i]<='z')){
            cout<<"No"<<endl;
            return 0;
        }
        if(i%2!=0&&s[i]!=' '){
            cout<<"No"<<endl;
            return 0;
        }
    }
    cout<<"Yes"<<endl;
    return 0;
}